Are geosynthetics used to their full potential?
Unsurprisingly no supplier believes geosynthetics are used to their full potential. Dave Woods, senior design engineer with Comtec, explains.
'The geosynthetics market (both UK and world-wide) is still in its infancy and will only become more widely used as benefits become apparent to general engineers.
'When we started constructing geosynthetically reinforced steep slopes over six years ago, all the structures we designed were submitted as alternatives to conventional solutions with the majority of our successful tenders being either highways works or larger private developments involving more forward thinking consultants.
'As the benefits - principally cost but also environmental, aesthetic and time related - have been more widely appreciated, smaller contractors have begun using reinforced soil as an alternative to conventional reinforced concrete, gabion and crib structures.
'At the same time consultants have begun to specify reinforced soil solutions on a more regular basis. There remain however a large number of schemes where other solutions are still preferred through either conservatism or ignorance of the benefits of integrated geotechnical solutions.
'It is this area of the market, together with the possibility of expanding the uses of geosynthetics, which leads us to believe that the UK market is still only 25% of its potential size. In other markets such as Hong Kong things are further back and geosynthetic solutions are still seen as radical departures from standard solutions to geotechnical problems.'
Have you encountered reluctance from a client to adopt a geosynthetic reliant design?
Every geosynthetic supplier has experienced negative attitudes to geosynthetic design. Frequently cited objections include doubts over durability or that 'a piece of plastic' is capable of doing the job, lack of track record, and involvement at a stage in a project when it is 'too late to change design'.
Occasional environmental objections to using 'plastic in the ground' are also mentioned, as are risks posed by vandalism or fire, maintenance requirements, the need for possible future excavations for services and aesthetics.
Most suppliers believe conservatism and a fear of the unknown are prevalent within the industry, as one commented 'in most of these cases objections mask a more deep seated mistrust of 'new and untried' solutions'.
What inhibits wider use of geosynthetics?
Suppliers were united in the view that the use of geosynthetics is hindered because it is not adequately covered in civil engineering undergraduate courses.
As Graham Thomson of Huesker says, 'polymer technology and behaviour must be introduced into university courses to stand alongside concrete and steel design'.
As suppliers see it, there is also reluctance among designers, consulting engineers and client bodies to embrace the wider applications of geosynthetics. They believe this may be because of the relative youth of the techniques and that there have been few proving grounds with projects that offer experimentation and research opportunities.
As one supplier says: 'Large-scale trials are too expensive for manufacturers to carry out independently given the uncertain market environment.'
Suppliers also said some engineers still believe that all geosynthetics are comparable to early basic separation fabrics. At least one supplier supported the specifiers' concerns over the lack of independent specifications which, if available, would give 'engineers the ability not to have to rely on manufacturers' supplied data'.
A number of suppliers hinted that in one respect they had scored an own goal by giving out contradictory information and advice to further their own sales.
Comtec's Dave Woods says: 'In promoting their own product it is often easier to point out faults in others in order to increase individual market share rather than working to increase the size of the market.'
Woods says the insular nature of the industry can lead to further mistrust and confusion. 'Since the relatively small number of manufacturers' products vary depending on their previous expertise, there are wide disparities in the very nature of products with essentially similar functions.
'By way of example, a reinforcement can realistically be a grid (punched, extruded or open weave with nominal thermal or mechanical bonds) or a textile (woven, tape or filament; or non woven, needle punched or callendared), or even a single strip (steel or polymer).
'This misrepresentation of factual data (such as creep in non-wovens or brittleness in grids) has led to products being deemed unusable under certain regulations/certifications where the problem actually exists in the test method failing to model in situ conditions,' says Woods.
'This has led to situations where reinforcement on a rail scheme in Germany may be a grid while over the border in Switzerland it would be a non- woven due to regulations being driven individual industry voices in each country rather than practical or financial concerns.
'The IGS as an impartial body does much to clarify the situation and present unbiased information, however the 'banter' between industry representatives - while entertaining in the context of a meeting - can be disconcerting when the opinions are voiced individually to a client who may already have reservations over the use of geosynthetics.'
What are the likely main growth areas for geosynthetics in the next decade?
Suppliers may have been cagey in their response, but the following were offered:
reinforced soil structures
geosynthetic barriers and reinforcement systems on brownfield sites